Apparatus for positioning wood pieces in the manufacture of consolidated wood sheet product



March 15, 1960 D. D. ADAMS ETAL APPARATUS FOR POSITIONING woon PIECES IN THE MANUFACTURE OF CONSOLIDATED woon SHEET PRODUCT 2 Sheets-Sheet 1 Filed Dec. 24, 1956 MarchlS, 1960 D. D. ADAMS EI'AL APPARATUS FOR POSITIONING WOOD PIECES IN THE MANUFACTURE OF CONSOLIDATED WOOD SHEET PRODUCT 2 Sheets-Sheet 2 Filed Dec. 24, 1956 a w: m3 m s s I m? H M m MA I A DG M MM 8 m u r DR V. B 3 m8 7 @8 I v8 mm m km. .PM M J mm mm F @N 4 M An g H fi kw NW mm X D ms QR Il i wF H LMWHfihQV 2i 0 on R x. n O O O R A mm mm 3 E. ,3 km .Qm mm rlzllll II \b N\ .QV Q\ United States Patent APPARATUS FOR POSITIONING WOOD PIECES IN THE MANUFACTURE OF CONSOLIDATED WOOD SHEET PRODUCT Donald D. Adams, Gresham, and Russell G. Brant, Portland, Oreg., assignors to Prentice Machine Works, Inc., Portland, Oreg., a corporation of Oregon Application December 24, 1956, Serial No. 630,296

6 Claims. (Cl. 144-281) This invention relates to apparatus for the manufacture of wood sheet material and more particularly to apparatus for positioning a series of wood pieces, as the pieces are readied for manufacture into a consolidated wood product, so as to compensate for irregularities in the dimensions of the wood pieces.

Many sheet materials are comprised of a series of elongated wood pieces which are butted together edge to edge and then secured in this position to form an extended sheet. Examples of such sheet materials are plywood and other composite board materials wherein one or more of the veneer lamina in the sheet are so prepared. In the manufacture of such materials, the veneer, prior to its incorporation in the finished board, is made into an extended sheet by bonding the edges of a series of abutting veneer segments together. This invention is particularly applicable to the manufacture of veneer sheets although it may be used in other ways such as in the manufacture of an extended sheet by abutting the lateral edges of pieces of lumber.

Generally, it is an object of this invention to provide apparatus for positioning a series of wood pieces arranged in laterally abutting relation whereby the tailing edge of the series of wood pieces may be adjusted as required for the reception of a succeeding wood piece subsequently added to the series.

In the manufacture of sheet material from wood pieces, the wood pieces are usually first trimmed so that their lateral edges approach being parallel to each other. Adhesive is applied to the edges of the wood pieces, and they are then consolidated into a sheet. The lateral edges of the wood pieces are usually not exactly parallel, however, so that when a sheet is prepared by abutting a series of wood pieces together, the tailing edge of the series of wood pieces tends to skew from a normal position relative to the length of the sheet prepared. This is undesirable as an attempt is made to maintain the grain structure of the sheet running perpendicularly of the length of the sheet. In addition, since the wood pieces are ordinarily rectangular in shape, deviations from a normal position of the joint between successive pairs of wood pieces results in a jagged edge extending along the side of the sheet which is formed. This creates waste because of the amount of trimming required. To obviate this waste and to properly maintain the grain structure of the wood in the sheet, it has been the practice to compensate for skewing of the edges of the wood pieces by inserting pieor wedge-shaped pieces in series with the wood pieces thereby to realing the tailing edge. Such a system requires visual inspection and manual handling of the wedge shaped inserts and, as a consequence, results in a considerable labor cost.

More specifically, this invention contemplates apparatus for abutting the edges of a series of wood pieces together which includes a conveyor for transporting the wood pieces and means for imparting a turning torque to the wood pieces as they are transported by the conveyer, the turning torque being applied in a direction which tends to compensate for skewing of the tailing edge of the series of wood pieces.

It is another object of this invention to provide such apparatus wherein the turning torque is applied to the wood pieces by varying the frictional grab of the conveyer section at opposite ends of the wood pieces.

More specifically, it is an object of the invention to provide apparatus of the sort described comprising a conveyer having pairs of continuous, oppositely disposed belts engaging opposite faces of the wood pieces transported which includes means for varying the relative spacing of co-operating pairs of the conveyer belts at opposite ends of the wood pieces and thus the frictional contact of the conveyer belts. By so varying the frictional contact of the conveyer belts, the normal resistance encountered in transporting the series of wood pieces serves to impart a turning torque to the wood pieces which can be controlled to properly position the series of wood pieces.

Another object of this invention is to provide such apparatus for adjusting the position of a series of wood pieces lying in laterally abutting relation wherein the amount of turning torque created is controlled automatically by a control mechanism operable to determine the position of the tailing edge of the wood pieces.

Yet another object of this invention is to provide apparatus for the edge gluing of wood pieces which is adapted to transport a series of wood pieces carrying a deposit of adhesive between their contiguous edges along a path through a drying section and so arranged that the sheet formed from the various segments may be turned in the path so as to accommodate the addition of successive wood pieces to the formed sheet.

A related object is to provide such edge gluing apparatus which includes means for determining the glue line lying along the edge of a wood piece which means is operable to send impulses to a conveyer mechanism for the apparatus and adjust the conveyer mechanism so as to position the wood pieces.

Still another object of this invention is to provide apparatus of the type described which includes an infeed conveyer operable to abut in a crowding relation successive wood pieces as they are positioned against a preceding series of arranged wood pieces.

These and other objects and advantages are attained by the present invention, various novel features of which will become more fully apparent from the following description taken in conjunction with the accompanying drawings wherein:

Fig. l is a top view of apparatus embodying this invention showing an infeed conveyer, an intermediate positioning conveyer, and a transport conveyer arranged in a path for transporting a series of wood pieces;

Fig. 2 is a section view along the line 2-2 of Fig. 1;; and

Fig. 3 is a diagrammatic view of a control means such as may be employed in the apparatus.

Referring in particular to Figs. 1 and 2, an embodiment of this invention comprises, in general, an infeed conveyer 10, an intermediate conveyer 11, and a transport conveyer 12 arranged in series and providing a path for the transport of elongated wood veneer pieces laterally through the apparatus. The veneer pieces are indicated in Fig. 1 by numerals 16 through 23. As illustrated im Fig. 1, the veneer pieces are fed laterally into the apparatus with their ends lying on opposite sides of the apparatus.

In the edge gluing apparatus illustrated, the veneer pieces are fed into the apparatus carrying a deposit of adhesive along both of their lateral edges. The infeed and intermediate conveyers are set up so that the veneer pieces are crowded together in the apparatus with their lateral edges tightly abutting each other. The adhesive carried between the edges serves, after it has dried, to bond the various veneer segments together thereby to form a continuous veneer sheet. Prior to their entry into the apparatus, the veneer pieces are trimmed so that their lateral edges approach being parallel to each other although, as explained hereinabove, in actual practice, the edges are never exactly parallel due to deviations occurring in the trimming operation. The apparatus includes means for turning the veneer pieces in the plane of their faces and along the plane of the path which they travel in the apparatus thereby to compensate for skewing of the veneer edges.

Infeed conveyer 10, intermediate conveyer 11, and transport conveyer 12 are suitably mounted in an appropriate frame structure comprised of longitudinal frame members 26 and transverse frame members 27. Each of the conveyers includes a lower or support conveyer section and an upper or clamping conveyer section, the upper and lower conveyer sections co-operating with each other to provide a maximum amount of traction for transporting the veneer sheets through the apparatus.

More specifically, infeed conveyer includes an upper conveyer section 31 and a lower conveyer section 32. Each of the conveyer sections is made up of series of elongated continuous belt members such as upper belt member 33 and lower belt member 34 arranged parallel to one another and in pairs with an upper belt member superimposed over a lower belt member. The upper belt members are provided at their opposite ends with driving belt pulley members 35 and driven belt pulley members 36. The lower belt members are similarly provided at their ends with driving belt pulley members 37 and driven belt pulley members 38. The driven belt pulley members for the upper and lower belts are rotatably mounted on a pair of shafts 39 and 40, respectively. The driving belt pulley members for the upper and lower belts are aflixed to a pair of upper and lower drive shafts 41 and 42, respectively. In operation, the drive is transmitted from the drive shafts to the belt pulleys by rotation of drive shafts 41, 42. Mechanism is provided for driving the lower shaft in a clockwise direction and the upper shaft in a counterclockwise direction as viewed in Fig. 2. Thus, proximate portions of the belt members travel from left to right as viewed in Figs. 1 and 2.

Intermediate conveyer 11 comprises an upper or clamping conveyer section 46 and a lower or support conveyer section 47. As in the case of infeed conveyer 10, each of the conveyer sections of the intermediate conveyer is made up of a series of continuous belts, upper and lower chain belts 51 and 52, respectively. The belts provided in the intermediate conveyer are chain belts, arranged parallel to one another and in pairs so that each of the chain belts in the upper conveyer section overlies a chain belt in the lower conveyer section. Opposite ends of chain belts 51 of the upper conveyer section engage a set of drive sprockets 53, and a set of driven sprockets 54. Chain belts 52 for the lower conveyer section are supported at their ends by driving sprockets 57 and driven sprockets 58. Sprockets 54 and 58 are rotatably supported on upper and lower drive shafts 41 and 42, and sprockets 53 and 57 are affixed to a pair of shafts 61 and 62 extending transversely of the apparatus. Since shafts 41 and 42 are power driven so as to rotate in a counterclockwise and clockwise direction, respectively, chain belts 51, 52 are rotated so that proximate portions of the chains travel fromleft to right as viewed in Fig. 2.

Interspersed with the chain belts of the intermediate conveyer are a series of upper and lower chain belts 71 and 72 of transport conveyer 12. As in the case of the infeed and intermediate conveyers, these chains are arranged in pairs with each of the upper chains superimposed over a lower chain and co-operating therewith to clamp against opposite faces of a veneer sheet. Driving sprockets 73 and 74 engage one end of the chains, these sprockets being afiixed to shafts 81 and 82. The chains at their other ends engage a series of driven sprockets 77 and 78. Sprockets 77 and 78 are rotatably mounted on shafts 75 and 76 extending transversely of the apparatus. Veneer discharged by transport conveyer 12 is carried in a conventional manner to the usual clipper mechanism (not shown) where the veneer sheet formed by bonding together the veneer pieces is cut by a clipper blade into preselected lengths. The clipper blade may be positioned directly at the discharge end of the transport conveyer, or an additional conveyer such as conveyer may be included between the transport conveyer and the clipper mechanism.

The chains in the upper and lower conveyer sections of the intermediate conveyer are each provided with a series of fiat top elements 83 afiixed to successive links in the chain. These elements increase the coefficient of friction between the chains and the veneer passing thereinbetween. Preferably, the chains of the transport conveyer are overlapped with the chains of the intermediate conveyer, as illustrated in Fig. 1. Overlapping of the chains prevents the edges of the veneer sheets from shifting with respect to each other as a result of the quite positive clamping action of the intermediate conveyer.

Each of the chains in the lower conveyer sections of intermediate conveyer 11 and transport conveyer 12 is provided with a support rail such as intermediate support rail 86 and transport support rail 87. These rails extend beneath a substantial portion of the chain and support the rollers of the chain as they ride over the rails. The rails are affixed at their ends to the transverse frame members of frame 12.

Vertically aligned with these support rails and extending a substantial distance along the chain belts for the upper sections of the intermediate and transport conveyers are a series of clamping rails or thrust bars 88 and 89. These rails are positioned directly above the rollers for the chains in these sections and are adapted to exert a clamping pressure downwardly toward support rails 86 and 87. Clamping rails 88 of the intermediate conveyer are provided at each of their ends with expansible hydraulic motors 91 and 92. Similarly, clamping rails 89 of the transport conveyer are provided at each of their ends with expansible hydraulic motors 93, 94. Conduits 96 and 97 connect motors 93, 94 to a conventional pump or other source of constant fluid pressure. Conduits 98, 99 connect motors 91, 92 to a control mechanism described hereinbelow which permits the fluid pressure in these motors to be varied in the manner to be described.

As noted hereinbefore, the lateral edges of veneer pieces, while tending to approach being parallel to each other, frequently deviate from this parallel position. To compensate for these irregularities, this invention provides mechanism for aligning the contiguous pieces of veneer so that the tailing edge of the abutted veneer pieces may be moved to a position lying normal to the path of the veneer through the apparatus.

Referring to Fig. 1, it will be noted that the tailing edge of veneer piece 17 is inclined from a normal position relative to the path of the veneer. By varying the pressure in motors 91, 92 at opposite ends of the veneer, motors 91, 92 constituting regulating means in the apparatus, the relative spacing of the chains in the upper and lowersections of intermediate conveyor 11 may be adjusted so that a diiferential in the clamping pressure exerted by the conveyor sections at opposite ends of the veneer piece may be created. This creates a turning torque in the veneer pieces lying between'the intermediate and transport conveyer sections which may be used to position'the tailing edge of veneer piece 17.

The pressure in regulating means or motors 91, 92 at opposite ends of the veneer may be adjusted manually in order to create a differential in the pressure at opposite ends of the veneer. However, in the preferred embodiment of this invention, the pressure in the motors is controlled automatically by control mechanism which includes a signal generating means generating signals created by deviations from a normal of a veneer edge as it passes a control point in the apparatus, and signal responsive means governing motors 91, 92.

Referring to Fig. 1, inwardly from the infeed conveyer at opposite sides of intermediate conveyor 11 are a pair of control stations 101 and 102, respectively. Each of the control stations comprises a pair of aligning contact pads 115 positioned above and below, respectively, opposite faces of the veneer as it travels through the apparatus and a pair of interrupt contact pads 120 positioned above and below, respectively, opposite faces of the veneer and inwardly from the aligning contact pads. A closed circuit between co-operating pairs of aligning contact pads and between co-operating pairs of interrupt contact pads is created when a glued edge passes between the pads by reason of the conductivity of the adhesive. The control stations are arranged so that when a closed circuit exists in either pair of the aligning contact pads exclusively of the other pair of aligning contact pads, an appropriate signal is delivered to valve mechanism or signal responsive means governing the air pressure connections for fluid motors 91, 92 located at opposite sides of the apparatus. The interrupt contact pads are included to prevent the aligning contact pads from operating during the interval that a glued veneer edge leaves the control stations.

The control mechanism including the signal generating means and valve means governing the air pressure in fluid motors 91, 92 is illustrated schematically for reasons of clarity in Fig. 3. The clamping rails or thrust bars of the intermediate conveyor which lie to the left of center of the apparatus, i.e., those lying in the apparatus at the upper part of Fig. l, are identified in Fig. 3 by the designations 88-L. Similarly the clamping rails which lie to the right of center of the apparatus, i.e., the lower part of Fig. l, are identified in Fig. 3 by the designations 88-R. Motors 91, 92 are clamping rails 88-L are connected to a fluid pressure conduit 103, and motors 91, 92 for clamping rails 88-R are connected to a fluid pressure conduit 104. The conduits are closed at their outer ends and are connected at their inner ends to a pair of valves 106 and 107, respectively. Valves 106 and 107 are of conventional construction and may be adjusted to connect conduits 103, 104 either to an exhaust port 108 or a supply conduit 109. These valves govern the pressure in motors 91, 92 and function as signal responsive means in the apparatus. A suitable electric motor 111, pump 112, and reservoir 113 is provided to deliver air under pressure to supply conduits 109.

The aligning contact pads of control stations 101, 102 are indicated in Fig. 3 at 115-L and 115-R, respectively. One of each pair of aligning contact pads is connected to a source conductor 117. The other of each pair of contact pads is connected through a solenoid to a second source conductor 118. The solenoid for contact pads 115-L is numbered 119, and the solenoid for contact pads 115-R is numbered 121. Solenoids 119, 121, as well as the other solenoids to be discussed herein, each have a movable armature which is spring biased to one extreme position so as to describe a to-and-fro movement when energized and de-energized, respectively. Solenoid 121 is ganged to a double pole double throw switch 122 and solenoid 119 is ganged to a double pole double throw switch 123. When solenoids 119, 121 are de-energized, switches 122, 123 occupy the position shown in Fig. 3.

One contact of switch 122 and one contact of switch 123 is connected to a source conductor 124. Another of the contacts of switch 122 is connected through a relay 6 126 and a solenoid 127 to a source conductor 128. Similarly, one of the contacts of switch 123 is connected through a relay 129 and a solenoid 131 to source conductor 128. The remaining pair of switch contacts for switch 122 are cross-connected to the remaining pair of switch contacts of switch 123.

Solenoids 127, 131 are ganged to valves 106 and 107, respectively. When the solenoids are de-energized, valves 106, 107 are both in a condition connecting supply conduits 109 to pressure conduits 103 and 104. Energizing of either solenoid positions the valve associated therewith so as to shut off supply conduit 109 and connect the pressure conduit for the valve to exhaust port 108.

From the above it will be apparent that if a closed circuit exists in either pair of aligning contact pads exclusively of the other pair of aligning contact pads an unbalanced condition is created whereby either solenoid 127 or 131 is energized. This results in a lowering of the fluid pressure in the fluid motors controlled by the,

solenoid which is energized and thus a decrease in the clamping pressure in that part of the intermediate conveyor where the fluid motors are located. For example, if the aligning contact pads of station 101 are closed by the passage of a glue edge therebetween and the aligning contact pads of station 102 remain open by reason of the fact that a glue edge has not yet reached control station 102, solenoids 119 and 127 are energized and valve 106 is adjusted to open conduit 103 to exhaust port 108. The clamping pressure at the left side of the intermediate conveyor is accordingly reduced. The resistance encountered by the veneer in passing through the apparatus causes the portion of veneer traveling along the left side of the conveyor to lag behind the portion of veneer traveling at the right side of the conveyor and, in this manner, a straightening of the veneer edge. Straightening continues until both pairs of aligning pads are closed by reason of a glue edge passing therebetween.

The interrupt contact pads for station 101 are indicated in Fig. 3 at 120-L, and the interrupt contact pads for station 102 are indicated in Fig. 3 at 120R. Without the inclusion of these pads, a veneer edge on leaving the control stations would activate the aligning contact pads in such a manner that the clamping rails would operate to turn the veneer pieces away from a straightened position. Thus, in the example just given, if the veneer edge was not completely straightened on leaving the control stations, the aligning contact pads of station 101 would be opened ahead of the aligning contact pads of station 102. This would result in contact pads -L being open and contact pads 115-R being closed and consequently the energizing of solenoid 131 independently of solenoid 127. As a result, clamping pressure would be decreased at the right side of the intermediate conveyer and the veneer pieces would be turned in a direction opposite to the direction in which they were originally turned. Interrupt contact pads -L and 120-R operate relays 129 and 126, respectively, which prevent solenoids 131 and 127 from operating during the passage of a veneer edge away from the control stations. The aligning contact pads and the interrupt contact pads together with the circuit associated therewith just described function as the signal generating means in the apparatus.

Means are provided for driving the drive pulley members and drive sprockets of the infeed, intermediate, and transport conveyers. Considering the upper conveyer sections of these conveyers, referring to Fig. 1, aflixed to projections of shafts 41 and 61 are a set of sprockets 141, 142, 143, and 144. A chain 146 engaging sprockets 142 and 144 connects for simultaneous rotation shafts 41 and 61. Drive is transmitted to shaft 41 by a drive chain 147 engaging sprocket 141, and a motor means (not shown) is included for driving chain 147. A chain 148 encircling sprocket 143 engages at its other end a sprocket 149 supported on shaft 81. Sprocket 149 is selectively connectable to shaft 81 by a conventional clutch indicated at 151 so as to rotate the shaft.- Clutch 151 is included to enable the transport conveyer to be stopped independently of the infeed and intermediate conveyer in the event that it is desired to increase the crowding of the veneer sheets in the transport conveyer. A similar drive system is provided for the chains and belts in the lower conveyer sections of the infeed, intermediate, and transport conveyers to enable both the upper and lower sections of the conveyers to be driven simultaneously.

conventionally, the conveyer belts of the infeed conveyer are driven at a slightly faster speed than the conveyer chain belts of the intermediate and transport conveyer. By so driving these conveyers, the veneer sheets tend to be crowded together upon reaching the intermediate conveyer. Thus, in Fig. 1, sprocket 142, which rotates shaft 41, is somewhat smaller than sprockets 143, 144, and 149.

In the edge gluing apparatus described, the transport conveyer passes through a drying chamber where the adhesive between the edges of the veneer pieces is dried. Drying of the adhesive may be accomplished in a number of ways, including either air drying apparatus or conventional radio frequency drying apparatus. The location of the heating chamber is generally indicated by the dotted outline 152. Details of the heating apparatus are not illustrated as it is not considered necessary for the understanding of this invention.

The infeed, intermediate, and transport conveyers may be driven continuously or they may be driven intermittently. In some operations, for instance, it may be desirable to drive the transport conveyer intermittently, particularly if relatively thick wood pieces are being processed.

It will be appreciated from the foregoing that there has been described novel apparatus which enables a series of wood pieces to be adjusted so that the tailing edge of the series may be properly positioned for the reception of a succeeding wood piece. The positioning is accomplished while transporting the series of wood pieces laterally along a path of movement through the apparatus. Thus, a novel method and apparatus have been disclosed which eliminates the necessity for manually inserting irregular wood pieces to compensate for the angle of the trailing edge in the series. 'Further, by providing control apparatus of the type illustrated, the entire alignment may be carried out automatically.

' While there has been described an embodiment of this invention, it is understood that various modifications and alterations may be made without departing from the inventive concept thereof, and it is desired to cover all modifications and arrangements which would be apparent to one skilled in the art and that come within the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In the manufacture of a lumber sheet, apparatus for positioning the contiguous longitudinal edges of elongated wood pieces arranged in series in laterally abutting relation comprising a frame structure, a conveyer sec tion mounted in said frame structure adapted to transport the series of wood pieces laterally along a path in said apparatus, said conveyer section including friction surfaces for engaging the faces of said wood pieces at opposite ends of said wood pieces, means driving said conveyer section, clamping means co-operating with said conveyer section for urging said wood pieces against said friction surfaces, regulating means operable to establish a differential in the frictional engagement of said friction surfaces at opposite ends of said wood pieces by adjustment of the relative position of said clamping means and said conveyor section, and control means governing said regulating means, said control means having signal means carried by said frame structure adjacet the path of said wood pieces operable to signal deviations from a standard position of the edge of a wood piece as it is transported in said path, and means connecting said signal means to said regulating means whereby the latter is actuated by signals generated by the former.

2. In the manufacture of a lumber sheet, apparatus for positioning the contiguous longitudinal edges of elongated wood pieces arranged in series in laterally abutting relation comprising a frame structure, a support conveyer section and a clamping conveyer section mounted in said frame structure and spaced from each other so as to frictionally engage opposite faces, respectively, of said wood pieces at opposite ends of the pieces while laterally transporting the same along a path in said apparatus, means for driving said support and clamping conveyer sections, regulating means operable to establish a differential in the frictional engagement of said support and clamping conveyer sections at opposite ends of said wood pieces by adjustment of the relative position of said clamping conveyer section and support conveyer section, and control means governing said regulating means, said control means having signal means carried by said frame structure adjacent the path of said wood pieces operable to signal deviations from a standard position of the edge of a wood piece as it is transported in said path, and means connecting said signal means to said regulating means whereby the latter is actuated by signals generated by the former.

3. In the manufacture of a lumber sheet, apparatus for positioning the contiguous longitudinal edges of elongated wood pieces arranged in series in laterally abutting relation comprising a frame structure, a support conveyer section mounted in said frame structure adapted to engage the lower faces of said wood pieces while transporting the series of wood pieces laterally along a path in said apparatus, said support conveyer section having a pair of continuous support belt members supporting op posite ends, respectively, of said wood pieces, a cooperating clamping conveyer section mounted in said frame structure and spaced from said support conveyer section so as to engage the upper faces of said wood pieces, said clamping conveyer section having a pair of continuous clamp belt members at opposite ends, respectively, of said wood pieces and superposed over said support belt members, means for driving said support and clamp belt members, a thrust member positioned above each of said clamp belt members mounted for movement toward said support conveyer section thereby to urge the clamp belt member against a support belt member, motor means operatively connected to each of said thrust members for moving each thrust member toward said support conveyer section, and control means governing said motor means, said control means having signal means carried by said frame structure adjacent the path of said wood pieces signaling deviations from a standard position of the edge of a wood piece as it is transported in said path, and means connecting said signal means to said motor means whereby the latter is actuated by signals generated by the former.

4. In the manufacture of a lumber sheet, the apparatus of claim 3 wherein the motor means comprises a pair of fluid motors connected at opposite ends of the thrust member, respectively, said control means regulating both fluid motors for each thrust member simultaneously.

5. In the manufacture of a lumber sheet, the apparatus of claim 4 wherein the control means for each fluid motor means is responsive to an electric signal means.

6. In the manufacture of a lumber sheet, apparatus for positioning the contiguous longitudinal edges of elongated wood pieces arranged in series in laterally abutting relation comprising a frame structure, a conveyer section mounted in said frame structure adapted to transport the series of wood pieces laterally along a path in said apparatus, means driving said conveyer section, clamping r1:1 e a g gsoperating with said conveyer section for urging longitudinally spaced portions of said wood pieces against said conveyer section, regulating means for adjusting the relative position of said clamping means and said conveyer section and operable to establish a difierential in the clamping pressure exerted 'by said clamping means at the longitudinally spaced portions of said wood pieces, and means mounted in said frame adjacent said path operable to determine the position of the edge of a wood piece as it is transported in said path, said last-mentioned References Cited in the file of this patent means being connected to said regulating means so as to 10 2,707,501

actuate said means.

UNITED STATES PATENTS Dickey Dec. 14, 1920 Weber Feb. 12, 1929 Dike Feb. 23, 1937 Miller July 21, 1942 Neller Nov. 24, 1942 Balch Dec. 14, 1954 Craik May 3, 1955 

